The prodigious
filtering of water by zebra mussels may also increase human and wildlife
exposure to organic pollutants (such as PCBs and PAHs). Early studies have
shown that zebra mussels can rapidly accumulate organic pollutants within
their tissues to levels more than 300,000 times greater than concentrations
in the environment. They also deposit these pollutants in their pseudofeces.

These persistent
contaminants can be passed up the food chain so that any fish or waterfowl
consuming zebra mussels may also accumulate these organic pollutants.
Likewise, human consumption of these same fish and waterfowl could result in
further risk of exposure. The implications for human health, however, remain
unclear.